:root {
    --primary-color: #4CAF50;
    --primary-dark: #388E3C;
    --text-color: #333;
    --light-gray: #f5f5f5;
    --white: #ffffff;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background-color: var(--light-gray);
    color: var(--text-color);
}

.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
}

.login-card {
    background: var(--white);
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    width: 100%;
    max-width: 420px;
    text-align: center;
    animation: fadeIn 0.5s ease;
}

.logo {
    margin-bottom: 2rem;
}

.logo img {
    width: 80px;
    height: 80px;
    margin-bottom: 1rem;
}

.logo h1 {
    font-size: 1.5rem;
    color: var(--primary-dark);
}

.form-group {
    position: relative;
    margin-bottom: 1.5rem;
}

.form-group i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: #999;
}

.form-group input {
    width: 100%;
    padding: 0.8rem 1rem 0.8rem 2.5rem;
    border: 1px solid #ddd;
    border-radius: 6px;
    font-size: 1rem;
    transition: all 0.3s;
}

.form-group input:focus {
    border-color: var(--primary-color);
    outline: none;
    box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.2);
}

.primary-btn {
    width: 100%;
    padding: 0.8rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

.primary-btn:hover {
    background-color: var(--primary-dark);
}

.primary-btn i {
    margin-right: 0.5rem;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}